Effects of Thickened Feeding on Gastroesophageal Reflux in Infants: A

Effects of Thickened Feeding on Gastroesophageal Reflux in Infants: A
Placebo-Controlled Crossover Study Using Intraluminal Impedance
Tobias G. Wenzl, Sabine Schneider, Frank Scheele, Jiri Silny, Gerhard Heimann and
Heino Skopnik
Pediatrics 2003;111;e355
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Effects of Thickened Feeding on Gastroesophageal Reflux in Infants:
A Placebo-Controlled Crossover Study Using Intraluminal Impedance
Tobias G. Wenzl, MD, MRCPCH*; Sabine Schneider, MD*; Frank Scheele, MD*; Jiri Silny, PhD‡;
Gerhard Heimann, MD, PhD*; and Heino Skopnik, MD, PhD*
ABSTRACT. Objective. Thickening of formula feedings is part of the therapeutic approach for gastroesophageal reflux (GER) in infants. However, its mechanism of
action, especially regarding the occurrence of nonacid
(pH >4) GER, has not yet been clearly described. The aim
of this randomized, placebo-controlled crossover study
was to examine the influence of formula thickened with
carob (St. John’s bread) bean gum on acid and nonacid
GER.
Methods. Infants with recurrent regurgitation and
without other symptoms were fed alternately (A-B-A-BA-B) with thickened (A) and nonthickened (B) but otherwise identical formula. Documentation of GER episodes during the study was performed by simultaneous
intraesophageal impedance measurement (intraluminal
electrical impedance; IMP) and pH monitoring. The IMP
technique is able to detect bolus movements inside a
luminal organ. The use of multiple measuring segments
on a single catheter allowed the analysis of direction,
height, and duration of the bolus transport. Continuous
videorecording and visual surveillance of regurgitation
frequency and amount resulted in a severity score.
Results. Fourteen infants (42 ⴞ 32 days old) were
examined during 6 feeding intervals each for a total
measuring time of 342 hours. A total of 1183 GER episodes and 83 episodes of regurgitation were registered.
Regurgitation frequency (15 vs 68 episodes) and amount
(severity score 0.6 vs 1.8) were significantly lower after
feedings with thickened formula. The difference regarding the occurrence of GER documented by IMP was also
pronounced (536 vs 647 episodes). Although not statistically significant, maximal height reached by the refluxate
in the esophagus was decreased after thickened feedings.
Mean GER duration and the frequency of acid (pH <4)
GER were not altered.
Conclusions. Thickened feeding has a significant effect on the reduction of regurgitation frequency and
amount in otherwise healthy infants. This effect is
caused by a reduction in the number of nonacid (pH >4)
GER episodes, but also because of a decrease of mean
reflux height reached in the esophagus. However, the
occurrence of acid GER is not reduced. The combination
of IMP and pH monitoring allows the complete registration and description of these GER episodes. Thickening
of formula feedings with carob bean gum is an efficient
therapy for uncomplicated GER in infants. Pediatrics
2003;111:e355–e359. URL: http://www.pediatrics.org/cgi/
content/full/111/4/e355; gastroesophageal reflux, infants,
From the *Kinderklinik and ‡Helmholtz-Institut fu¨r Biomedizinische Technik, Universita¨tsklinikum Aachen, Aachen, Germany.
Received for publication Jul 29, 2002; accepted Dec 2, 2002.
Reprint requests to (T.G.W.) Kinderklinik, Universita¨tsklinikum Aachen,
Pauwelsstr. 30, D 52074 Aachen, Germany. E-mail: [email protected]
PEDIATRICS (ISSN 0031 4005). Copyright © 2003 by the American Academy of Pediatrics.
thickened feeding, intraluminal electrical impedance technique, placebo-controlled study.
ABBREVIATIONS. GER, gastroesophageal reflux; IMP, intraluminal electrical impedance; Formula A, thickened; Formula B, nonthickened.
T
he thickening of formula feedings is part of
the stepwise therapeutic approach for gastroesophageal reflux (GER) in infants.1– 4 Esophageal pH monitoring is considered a standard test to
diagnose GER.3,5,6 However, buffering gastric acidity
and frequent feeding of infants are known to prolong
periods of hypoacidity, and, especially after feedings, reflux events with pH ⬎4 are not detected by
pH monitoring.7,8 Even so, to investigate the effects
of thickened (Formula A) feedings, most studies relied on the validity of esophageal pH monitoring for
the diagnosis of GER.9 –13
Carob (St. John⬘s bread) bean gum is a galactomannan, which is refined from the carob tree, Ceratonia
siliqua. Both rice cereal and bean gum are used in
dietary preparations as thickening agents. As opposed to rice cereal, which is broken down by salivary amylase, bean gum is not split by these enzymes and thus maintains its thickening effect also
after reaching the stomach. It provides no nutritional
value and does not alter the energy distribution of
infant formula.2
The objective of this prospective, randomized, placebo-controlled crossover study was to evaluate the
effect of formula thickened with carob bean gum2 on
the number and the characteristics of acid (pH ⬍4)
and nonacid (pH ⬎4) GER events by using a combination of pH monitoring and the pH-independent
multiple intraluminal electrical impedance (IMP)
technique.8,14 –17
METHODS
Otherwise healthy infants with recurrent regurgitation that
fulfilled the inclusion criteria (Table 1) were evaluated. During the
initial surveillance period of 3 consecutive days, regurgitation
frequency and amount were documented. To exclude GER secondary to other medical conditions, the following prestudy examinations were performed: complete blood count, total immunoglobulin E, radioallergosorbent test (cow⬘s milk protein, casein,
␣-lactalbumin, ␤-lactoglobulin), skin prick test (formula before
study entry, both study formulas, normal saline, histamine), ultrasound of the abdomen and head, urinalysis, and stool cultures.
Any abnormal finding from these examinations resulted in exclusion from the study. During the following 24-hour prestudy
phase, all included infants were switched from their initial formula to Formula B (Table 2).
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e355
TABLE 1.
Inclusion and Exclusion Criteria for Infants Entering Study
Inclusion Criteria
Exclusion Criteria
Recurrent regurgitations: ⬎5 regurgitations
of at least a small volume (5 mL), or at
least 1 regurgitation of at least half of the
feeding per day, during a surveillance
period of 3 consecutive d
⬍4 mo old
Body weight ⬎2000 g
Exclusively formula-fed
No or ⬍5 regurgitations of a small volume
(5 mL) per d, during a surveillance
period of 3 consecutive d
Suspected food allergy
Gastroenteritis
Other acute infection
Apneas and/or bradycardias
Regurgitation secondary to other cause
Medication influencing esophageal motility
Investigation for GER was performed by combined measurement of intraesophageal pH and multiple electrical impedance.8,17
The principle of IMP registration is based on the measurement of
electrical impedance changes between 2 neighboring electrodes
during the passage of a bolus inside a luminal organ. By arranging
multiple electrodes sequentially on a catheter, the direction of
bolus movement can be described. In this study, a single flexible
catheter with 7 impedance electrodes (outer diameter 1.5 mm),
representing 6 bipolar impedance channels (Helmholtz-Institut
fu¨ r Biomedizinische Technik, Aachen, Germany), and a pH-sensitive antimony electrode was used. A GER episode is defined as
a decrease in impedance starting in the most distal channel and
subsequently extending orally to the more proximal channels. The
catheter was passed transnasally under fluoroscopy. The distance
between each impedance electrode was 1.5 cm, resulting in a total
measuring length of 9 cm. Measuring segments were positioned
from just above the cardia (channel 6) to the pharynx (channel 1),
with the pH sensor situated at the level of channel 5, ie, ⬃3 cm
above the gastroesophageal junction. The acquisition rate of pH
and impedance signals was 50 Hz per channel.
The infants were randomized to receive the 2 study formulas in
an alternate fashion. The order of treatment was randomly assigned by a computer-generated method with the individual infant as the unit of randomization. Formula A contained 0.4% carob
bean gum and was otherwise identical with Formula B (Table 2).
During the study period, group I received alternate feedings beginning with Formula A (A-B-A-B-A-B) and group II received
alternate feedings beginning with Formula B (B-A-B-A-B-A), according to the crossover study design and their randomization.
Study formulas were prepared by a second independent caregiver
after breaking the randomization code. The study phase lasted for
at least 24 hours and at least 6 feedings, and was continued for at
least 2 hours after the sixth feeding. During the study, each infant
was fed with its individual feeding intervals and by the same
caregiver. The study groups (I or II) were blinded to the investigators during the study and the data analysis.
Regurgitation amount and time were documented in a protocol
by continuous visual surveillance and by continuous videorecording. The amount of a single regurgitation was scored visually as:
ⱕ5 mL; ⬎5 mL; about half of the feeding; or the complete feeding.
The online regurgitation protocol was verified and eventually
amended by analysis of the videorecording. Severity of regurgitations after a single feeding was quantified by a scoring system
(Table 3).11
All impedance and pH data were stored simultaneously in a
computer system at bedside. Data analysis for GER events was
performed using custom software (Motility; Helmholtz-Institut
fu¨ r Biomedizinische Technik, Aachen, Germany) and visual validation. Impedance recordings were visually analyzed for the typical IMP pattern of GER, indicated by a retrograde esophageal
TABLE 2.
Composition of Formula A and Formula B
Formula A and B
Per 100 g
Powder
Per 100 mL
Formula
Energy (kcal)
Protein (g)
Whey:casein
Lipids (g)
Carbohydrate (g)
Additionally in Formula A
Carob bean gum (g)
467
12.2
20:80
21
58
66
1.72
20:80
3.0
8.2
3
.4
e356
TABLE 3.
Regurgitation Score After a Single Feeding
Score
Severity
0
1
2
No regurgitation
1 regurgitation of ⱕ5 mL
2 regurgitations of ⱕ5 mL, and/or 1 regurgitation
of ⬎5 mL
⬎2 regurgitations of ⱕ5 mL, and/or ⬍3 regurgitations
of ⬎5 mL
ⱖ3 regurgitations of ⬎5 mL
Regurgitation of about half of the feeding
Regurgitation of the complete feeding
3
4
5
6
volume flow (Fig. 1). In this study, GER was diagnosed only if this
typical pattern was noted in the esophageal impedance.
Documentation during each GER included the minimal pH
value, the maximal height reached by the refluxate in the esophagus, and the duration of GER. GER duration was defined as time
after the onset of a reflux episode needed to reach 50% of the initial
impedance value in the most distal impedance channel (channel
6), which corresponds to a clearance ⬎90% of the reflux volume in
the measuring segment.8
Mean values were calculated for most parameters, including
regurgitation score and reflux height, eventually resulting in “virtual” decimal values (Tables 4 and 5). Statistical analysis was
performed using the paired Wilcoxon test (SAS/STAT 8.01; SAS
Institute, Cary, NC). Significance was established by a value of
P ⬍ 0.05.
The study protocol was approved by the Ethics Committee of
the Medical Faculty of the University Aachen (Aachen, Germany).
Before beginning any evaluation of an infant, written informed
consent was obtained from the parents.
RESULTS
Fourteen infants (mean age at study 42 ⫾ 32 days;
9 female, 5 male) that fulfilled the inclusion criteria
were examined. There were no dropouts during the
prestudy or the study phase. No infant showed signs
of a secondary cause of GER or regurgitation. Seven
infants were randomized to study group I, and 7
infants to study group II. The study formula was
tolerated well by all infants.
During a total measuring time of 342 hours, 83
regurgitations (15 after Formula A, 68 after Formula
B; P ⬍ .0003) were documented by visual surveillance and video analysis. Calculated from 3 feeding
periods in each infant, the mean regurgitation score
for a single feeding was 0.6 after Formula A, and 1.8
after Formula B (P ⬍ .003). Seven infants (50%) did
not regurgitate at all after Formula A; 1 (7%) of these
7 infants also did not regurgitate at all after Formula
B.
A total of 1183 GER episodes (536 after Formula A,
647 after Formula B; P ⬍ .02) were detected by the
typical pattern in the impedance tracings. Reflux
events occurred in all patients. For technical reasons
THICKENED FEEDING AND GASTROESOPHAGEAL REFLUX
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Fig 1. Original tracing of a typical nonacid
GER. The retrograde esophageal bolus passage
is characterized by a decrease of impedance (Z)
starting in the most distal channel (Z6) and
subsequently extending orally to the most
proximal channel (Z1). The pH is remaining ⬎4
throughout the entire GER episode. The pH
sensor is situated at the level of channel 5; the
arrow indicates the bolus passage from distal to
proximal.
TABLE 4.
Details of GER Episodes in Individual Infants: 3 Feedings of Formula A Versus 3 Feedings of Formula B
Patient Group
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
II
II
I
I
II
I
II
I
I
II
II
I
II
I
Regurgitation
Frequency (n)
After Formula
Regurgitation
Score After
Formula
GER Episodes (n)
After Formula
GER Height
(Impedance Channel)
After Formula
GER Duration
(Seconds) After
Formula
Acid GER (n)
After Formula
A
B
A
B
A
B
A
B
A
B
A
B
3
1
0
6
0
0
0
1
1
0
0
0
1
2
14
2
2
12
0
2
7
7
3
2
4
5
2
6
6.5
1.0
0
7.5
0
0
0
1.0
5.0
0
0
0
1.0
3.5
9.5
10.0
2.0
7.5
0
2.0
5.5
6.5
3.0
2.0
5.0
5.0
2.0
13.5
73
12
7
64
27
36
49
67
43
27
28
28
23
52
96
25
22
56
36
39
53
82
38
40
39
51
28
42
2.6
3.2
3.3
2.2
2.9
2.6
2.7
2.2
2.0
2.6
2.9
2.5
2.6
2.2
2.8
2.5
3.0
2.1
2.4
2.5
2.6
2.2
1.9
2.9
2.6
2.2
2.8
2.0
15.4
22.0
56.3
22.8
32.5
30.7
56.0
29.3
52.3
20.7
26.5
43.3
48.2
50.3
13.1
36.7
85.5
17.5
32.3
31.4
35.7
26.9
32.3
20.2
19.5
28.6
67.4
28.4
43
3
2
20
17
5
24
27
2
1
10
6
4
13
59
3
14
26
13
4
28
21
3
1
11
4
4
9
All figures calculated as mean values, resulting in “virtual” decimal values for regurgitation score and GER height.
(Group I: infants fed A-B-A-B-A-B; Group II: infants fed B-A-B-A-B-A).
the pH of 5 GER in 1 patient (number 11) could not
be determined. A total of 377 (32.0%) GER were
acidic (pH ⬍4), and 4 (0.3%) alkaline episodes (pH
⬎7) were recorded. Calculated mean GER height
was impedance channel 2.6 after Formula A, and
impedance channel 2.5 after Formula B (P ⫽ .08),
with channel 1 being the most proximal channel.
Mean GER duration was 36.2 seconds after Formula
A, and 33.9 seconds after Formula B (P ⫽ .3). The
number of acid GER episodes (pH ⬍4) was 177 after
Formula A and 200 after Formula B (P ⫽ .6).
The majority of reflux events was nonacid (801
nonacid GER vs 377 acid GER; P ⬍ .007). Calculated
mean GER height was impedance channel 2.5 during
a nonacid GER, and impedance channel 2.6 during
an acid GER (P ⫽ .2). Mean GER duration of a
nonacid GER was 30.4 seconds, and of an acid GER
43.1 seconds (P ⬍ .05).
Data from individual infants are summarized in
Tables 4 and 5.
DISCUSSION
There has been controversial discussion as to
whether there is a place for thickened feeding in the
therapeutic regimen for GER in infants.1,4,18 However, in most studies examining this question, the
diagnostic tool used to detect GER episodes was pH
monitoring.3,5,6 Various authors using pH monitor-
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e357
TABLE 5.
Patient
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Details of GER Episodes in Individual Infants After 6 Feedings: Nonacid (pH ⬎4) Versus Acid (pH ⬍4) GER
Group
II
II
I
I
II
I
II
I
I
II
II
I
II
I
GER Episodes (n)
GER Height
(Impedance Channel)
GER Duration
(Seconds)
Nonacid
Acid
Nonacid
Acid
Nonacid
Acid
67
31
13
74
33
66
50
101
76
65
41
69
43
72
102
6
16
46
30
9
52
48
5
2
21
10
8
22
2.6
2.7
3.4
2.2
2.6
2.4
2.6
2.2
2.0
2.8
2.7
2.3
2.6
2.1
2.8
3.2
2.8
2.2
2.7
3.2
2.8
2.3
1.8
2.5
2.9
2.6
3.1
2.0
10.2
24.4
36.5
20.0
33.9
29.3
27.5
28.0
44.7
20.3
20.4
31.0
58.0
40.7
16.7
66.7
112.6
20.9
30.7
44.6
62.7
27.9
16.4
23.0
25.9
53.1
62.5
39.8
All figures calculated as mean values, resulting in “virtual” decimal values for GER height.
(Group I: infants fed A-B-A-B-A-B; Group II: infants fed B-A-B-A-B-A).
ing in their studies did not find a significant influence on acid (pH ⬍4) GER.9,10,13 It is known from
previous studies that the majority of reflux events in
the infant age group are nonacid (pH ⬎4), especially
because of postprandial gastric neutralization after
milk feedings.7,8 These GER episodes are undetectable by pH monitoring.17 Therefore, we used the
pH-independent IMP technique in combination with
pH monitoring7,8,14 and continuous visual and video
surveillance.
To exclude secondary causes of GER, infants were
evaluated carefully before entering the study.11 To
exclude an influence of the different infant formulas
fed before the study on the results, all infants received the same Formula B during the final prestudy
day. To exclude interference by handling variation
because of caregiver experience, each individual infant was fed by the same caregiver during the whole
study phase. Initially, the study was designed as
double-blind and placebo-controlled. When applying strict study criteria, we found that by their appearance the 2 study formulas could be distinguished by experienced personnel. Therefore,
“double-blind” was deleted from the study design.
However, during data analysis, the study groups,
and thus the order of treatment, were blinded to the
investigators. Furthermore, in the chosen crossover
design, each individual infant served as its own control.
There was a significant decrease of regurgitation
frequency and amount (score) after feeding Formula
A. Half of the infants did not regurgitate at all after
Formula A. This effect was mostly caused by a significant reduction of GER episodes after Formula A,
with GER events occurring in every single infant.
It is known from previous studies8 that most GER
episodes reach the uppermost impedance channel
(channel 1, located in the pharynx). This is true for
GER with and without regurgitation. In light of these
findings, the slight reduction of reflux height reached
in the esophagus after Formula A, although not statistically significant (P ⫽ .08), probably also contributed to the decrease of regurgitation frequency.19
However, there was no significant difference in
e358
reflux height regarding acid versus nonacid GER. As
demonstrated previously,10,13 the occurrence of acid
(pH ⬍4) GER was not significantly reduced after
thickened feeding. Because the majority (68%) of reflux events was nonacidic (pH ⬎4), one must assume
that especially their reduction led to a decrease of
regurgitation frequency. Alkaline (pH ⬎7) GER episodes were rare (0.3%), and their role is not yet clear
in this age group.
There has been concern about a suspected increase
of regurgitation amount after thickened feeding as a
result of delayed retrograde and anterograde gastroesophageal motility.9 This could not be confirmed by
our study results. Mean GER duration was not significantly prolonged after feeding Formula A. As
expected from previous studies using pH monitoring
and impedance,8,15 the duration of acid GER was
longer than that of nonacid GER. This is because of a
delay of acid clearance versus volume clearance.
The effects of thickened feeding were analyzed in
detail with this study. The combination of pH and
impedance measurement was able to deliver valuable new information regarding gastroesophageal
motility.7 We conclude from our results that formula
thickened with carob bean gum2 is an efficient therapy for uncomplicated GER and regurgitation in infants. There is an obvious advantage of using prethickened feedings versus individually added
thickener regarding hygiene and handling. Following the recommendations, thickened formula should
only be used under medical supervision and after
parental advice and reassurance.1,3,18,20,21
ACKNOWLEDGMENTS
We thank the nurses of the Fru¨ h und Neugeborenen Station,
Universita¨ tsklinikum Aachen, Germany, for their enormous support during the study; Dr Ing. Morten Trachterna for his technical
expertise; and Dipl. Math. Thorsten Reineke for statistical advice.
This study was supported in part by a grant (87/96-S1; to
T.G.W.) from START, Medizinische Fakulta¨ t, Rheinisch-Westfa¨ lische Technische Hochschule Aachen, Germany. The work was
published previously in abstract form (J Pediatr Gastroenterol Nutr.
2000;31:S206).
Study formulas were provided by Milupa, Friedrichsdorf, Germany.
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Effects of Thickened Feeding on Gastroesophageal Reflux in Infants: A
Placebo-Controlled Crossover Study Using Intraluminal Impedance
Tobias G. Wenzl, Sabine Schneider, Frank Scheele, Jiri Silny, Gerhard Heimann and
Heino Skopnik
Pediatrics 2003;111;e355
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